Antenna for directed rays



2 Sheets-Sheet l INVENTOR RUDOLF BECH MAN N BY MM ATTORNEY Oct. 22, 1935. R. BECHMANN ANTENNA FOR DIRECTED RAYS Filed March 23, 1955 Oct. 22, 1935. R. BEQHMANN 2,018,342

ANTENNA FOR DIRECTED RAYS Filed March 25, 1933 2 SheetsSheet 2 INVENT RUDOLF BE ANN ATTORNEY Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE ANTENNA FOR DIRECTED RAYS tion of Germany Application March. 23, 1933, Serial No. 662,293 In Germany March 23, 1932 3 Claims.

For concentrating short wave directed rays it is known to use antennae that are large in one or two directions with respect to the wave length. The concentration of the energy radiated from such antennae is substantially determined by the proportionality existing between these dimensions and the wave length. There are two essential embodiments known. According to one embodiment, one line or one surface is provided with di-poles oscillating at equal phase. A concentrated ray is formed at right angle to this line or surface. A known embodiment which may here be considered is a surface antenna comprising di-poles at equal phase of the length of one alternation. Such anv antenna system is shown in Figure 1. The di-poles are arranged in a vertical plane and are excited at equal phase. To this end the Lecher wire connections of every second pair of di-poles must be crossed as is clearly shown in the figure. For the purpose of adaptability a transformer T is also placed between the power line and the antenna system. The number of elements are assumed to be equal to M N. Figure 4 shows the directional characteristic in a plane including one line of ray elements for N=2, 4 and 8, (a) (b), respectively.

The other system above referred to consists of elements arranged in the direction of concentration and spaced apart from each other by a distance of approximately one alternation, whereby however the successive elements are excited at opposite phase. Figure 2 represents such an arrangement and the manner of feeding a horizontal di-pole line. As already mentioned in the preceding part of the description the 'di-poles disposed behind each other must be supplied at opposite phase. This is indicated by the signs and In view of this requirement the connections to the Lecher wires cannot be crossed in this case. The radiation diagram, in neglecting the elementary characteristic of the transmitters is symmetrical, as regards rotation around the axis aa and has about the shape of a club. The directional characteristic is shown in Figure for 4, 8 and 16 elements (a), (b), (0) respectively.

The invention is described in more detail in the following specification which is accompanied by drawings, wherein Figures 1 and 2 show known antenna structures, and Figure 3 shows an antenna in accordance with the present invention. Figures 4, 5 and 6 are curves illustrating the radiation patterns of the antenna structures of Figures 1, 2 and 3 respectively.

According to the invention an essentially higher directional concentration is obtained with smaller geometrical dimensions of the antenna system by a directive geometrical antenna. The radiating elements forming a geometrical system are arranged in such manner that the elements of each individual surface are excited at equal '5 phase in respect to each other while the elements of successive surfaces are excited at opposite phase. It is known that such excitation can be accomplished by feeding through Lecher wires. Figure 3 shows a geometrical antenna system of this type. Figure 3 shows the spacial directional antenna system in accordance with the present invention. It has already been pointed out in the description that all di-poles disposed in a vertical plane must oscillate at equal phase, but 15 that, however, between the various planes disposed behind one another there must be opposite phase. In the embodiment shown by way of example the superposed di-poles are connected to vertical supply lines s1, s2 The supply lines s1, 84, 8585 disposed behind each other are connected to two horizontal Lecher wires hl, ha which are interconnected by a cross wire ha and are connected across an adapting transformer T to the power line h4 connected to the transmitter.

As the figure shows the leads of every second pair of di-poles to the vertical supply lines s1, s2 are crossed while the vertical supply wires themselves are connected to the horizontal supply wires 71. and its without crossing. It must be emphasized that Figure 3 is not the only possible embodiment. The horizontal di-pole lines may also be connected by horizontal supply wires as in Figure 2 (for the same number of di-poles, 8 horizontal wires would, therefore, be used) and the latter could be connected to two vertical supply wires.

There may be M -surfaces combined each forming N N elements. Figure 6 shows the radiation characteristic obtained for the following cases:

(a) M=4 N=4 The above described arrangement radiates in two opposite directions. In accordance with the invention the radiation is suppressed in one direction by the combination of two radiating systems of same type in which the one system is spaced apart from the other system in the direction of radiation by a distance equal to one-fourth wave length and in which all elements of the one group 7 have a phase shifted by with respect to theelements of the other group.

According toa further feature of the invention the two systems may be arranged within each other in such manner that always two element surfaces are spaced apart from each other in the direction of radiation by the distance equal to one-fourth wave length and the difference in phase always for two successive surfaces whose elements proper are all excited at equal phase, is equal to g 2 I'claim: V 1. A'directional antenna array of three dimensions comprising a plurality of spaced simple dipole antenna units arrangedin the same ver- 'tical plane and oscillating in the same phase, and

another plurality of spaced simple dipole antenna units arranged in another vertical plane which is 1 wave length coupling together said vertical transmission lines.

2. A directional antenna array of three dimen-V sions for obtaining wave concentration in the horizontal plane comprising a plurality of spaced dipoles arranged in the same vertical plane, vertical feeder lines for said dipoles, alternate dipoles being coupled with crossed connections to said feeder lines whereby all of said dipoles in said plane oscillate in the same phase, another similar plurality of dipoles in another vertical plane which is parallel to and spaced apart from said first plane a distance equal to an odd multiple 7 of half the wave length, and a transmission line supplying power to and connecting together the vertical feeders of the dipoles in both said planes 7 whereby the dipoles in one plane oscillate at opposite phase with respect to the dipoles in the other plane,

3. A directional geometrical antenna system for obtaining wave concentration in the'horizontal plane comprising a plurality of antenna sections lying in a vertical plane and spaced apart trans versely in the direction of desired communication, each of said. antenna sections comprising a single unbroken pair of vertical linear feed leads and a plurality of horizontal radiators coupled to the feed leads, alternate radiators of each section being coupled with crossed connections for cophasal excitation, and a symmetrical feeder sys-- tem for coupling the vertical feed leads of the sections in said plane cophasally, and another similar plurality of antenna sections lying in another vertical plane which is parallel to said first vertical plane and. spaced apart therefrom a distance equal to an odd multiple of a half wave length, and feeder leads coupling together the symmetrical feeder systems of both of said planes.

RUDOLF BECHMANN. 

